Assuming...
1. there's ample gap between the pads - ie. its only rubbing on one pad, not both, and
2. the rotor is true - ie. it rubs all the time, not just one momentary contact as the wheel rotates...

Then it sounds like simple issue of rotor not centred between pads in caliper. It could be as easy as loosening your front QR, re-positioning wheel and tightening. If this doesn't solve it, then you'll need to undo the two allen bolts holding the caliper to the posts on your front fork, position it so that the rotor is equi-distant between pads, and tighten without it moving out of position again. Its the last bit thats tricky, and will take a few attempts to get the knack.

Its not tricky, just hold the lever while you tighten the caliper bolts.

No, no, no! This is not the way to center a caliper! The caliper may "walk" and you won't know it, meaning as you torque the mounting bolt, the turning and tightening of the mounting bolt may cause the caliper to move slightly which would render you efforts worthless.

The BEST WAY to align a caliper is to do it VISUALLY.

BUT...first try to tighten the QR (quick release) to see if this realigns the caliper to the rotor....if not:

1) Look down through the caliper from above (front brake) so that you can see the pads and the rotor. If you own a bike work stand, hang your bike on it first.

2) Spin the wheel. Is the pad or pads making consistant contact? If not, the rotor needs trueing. If yes, is it one pad or both pads? If it is one pad, loosen the caliper mounting bolts and then retighten them to just less than "hand tight". Gently move the caliper (while still looking down through it from above) so that you can see an ever so slight gap between both pads and the caliper. Then...

3) SLOWLY, carefully (while still watching from above) tighten the mounting bolts. Check to see if the caliper still looks centered?? Spin the wheel, any contact? Spin it again and apply the brake, then release the lever after the wheel stops. Look down through the caliper again, how's the gap between both pads and the caliper???

Do this until you get the caliper to stay centered. It may take a few attempts and having any mechanical ability is a big help.

If both pads are making contact, there may be too much fluid in the system or the pistons may be sticking. That's a whole other ballgame.

Have to agree with ambassadorhawg on that one. Although 'compress the lever and tighten' has kinda worked as a get-home fix out on the trail, the forces put on the allen bolts to get them up to the right torque always seems to skew it back out of alignment, even with the lever depressed. So, when I want to do it accurately, its by sight. Just my experience - good if it works for you....